Part 39 (2/2)

Four half-tone illustrations: 1 The Settling Basin at the Water Works

2 Interior of the Tunnel Through which the Water is Pumped

3 Where Detroit's Water Co Basin

GUARDING A CITY'S WATER SUPPLY

HOW THE CITY CHEMIST WATCHES FOR THE APPEARANCE OF DEADLY BACILLI; WATER MADE PURE BY CHEMICALS

BY HENRY J RICHMOND

”COLON” The city chenificant word as he set down the test tube into which he had been gazing intently The next e of all the city papers displayed the warning, ”Citizens should boil the drinking water”

Every , as the first task of the day, the city che a few spoonsful of very ordinary bouillon, akin to that which you rab at the quick lunch, but which has been treated by the adins in a bulb which holds the fluid and terminates in an upturned crook sealed at the end Into this interesting little piece of apparatus, the che water, and he then puts the whole into an incubator where it is kept at a temperature favorable to the reactions which are expected if the water is contaminated

After a sufficient ti appears The bouillon still reed Its color and clearness have not been affected

But the cheh in the closed end of the tube as it did when placed in the incubator The observation seenificant

What has happened? The water contained soanisms which when acted upon by the chemical in the tube have set up a fermentation

Gradually, one by one in the little bulb, bubbles of gas have formed and risen to the surface of the liquid in the closed upper end of the tube

As this gas was liberated, it took the place of the liquid in the tube, and the liquid was forced doard until there was quite a large space, apparently vacant but really filled with gas

It was this phenomenon that had attracted the attention of the chemist

What did itfurnished to the city for half a anish to in to take an interest It was not, however, in itself a danger signal

Not all bacterial life is a menace to health, the chemist will tell you

Indeed, humanity has come to live on very peaceable terms with several thousand varieties of bacteria and to be really at enmity with but a score or more Without the beneficent work of a certain class of bacteria the world would not be habitable This coh rather repulsive condition--the necessity of getting rid of the dead to

What would be the result if no provision had been ration of the bodies of all the inning? Such a situation is inconceivable But very wisely providence has provided that myriads andup worn-out and dead aniinal elements These eleetable growth and ain for the nourish the et the notion that all bacteria are our mortal foes We could not live without theer be habitable

Neither need we fear the presence of bacterial life in our drinking water Drinking water always contains bacteria We, ourselves, even when in the best of health, are the hosts of millions upon millions of them, and it is fair to suppose that they serve some useful purpose At any rate, it has never been demonstrated that they do us any harm under normal conditions